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diff --git a/doc/krita/using-colorspaces.docbook b/doc/krita/using-colorspaces.docbook deleted file mode 100644 index 0222e8d3d..000000000 --- a/doc/krita/using-colorspaces.docbook +++ /dev/null @@ -1,149 +0,0 @@ -<chapter id="colorspaces"> -<title>Colorspaces</title> - -<para> -This chapter gives information on what colorspaces are, which colorspaces -&krita; offers, and what you should keep in mind when using them. -</para> - -<sect1 id="colorspaces-intro"> -<title>Introduction to colorspaces</title> - -<sect2 id="colorspaces-intro-whatis"> -<title>What is a colorspace?</title> - -<para> -In short, a colorspace is a way to represent colors by specifying a number of -parameters. As parameters, one can choose for example the amounts of red, -green and blue light needed for the color. This results in the commonly known -RGB colorspace. One can visualize this as a three-dimensional space, with each -of the red, green, and blue light components being an axis in the colorspace. -A color then corresponds to a certain point in this colorspace, defined by its -coordinates on the three axes. -</para> -<note><para> -To be more precise, a colorspace is a combination of a color model (indicating -which axes are present) and a mapping function (indicating which values -correspond to which colors). -</para></note> -<para> -Not every color can be represented in every colorspace. Some colorspaces -define more, or different, colors than others. The set of colors that can be -represented in a certain colorspace is called its gamut. Because gamuts -can differ widely, it is not guaranteed that images in a certain colorspace -can be converted to another colorspace without having to substitute certain -colors for others, even if they are based on the same color model. -</para> - -</sect2> - -</sect1> - -<sect1 id="colorspaces-list"> -<title>Available colorspaces</title> - -<para> -&krita; offers colorspaces based on RGB, CMYK, Lab, LMS, YCbCr, and Gray -color models. These are shortly discussed in this section. -</para> - -<sect2 id="colorspaces-list-rgb"> -<title>The RGB color models</title> - -<para> -The abbreviation RGB stands for Red, Green, Blue, and the color model with -this name refers to the three light components that are emitted in displays -(televisions, computer monitors, etcetera) to create a certain color. This -color model is used by default in virtually any standard painting application. -</para><para> -When defining a color in the RGB model, its red, green and blue components are -specified. If all components are absent (each component is emitted at 0 -percent intensity, so no light at all), the color is pure black. If all -components are fully present (100 percent intensity), the color is pure white. -If one component is present at full intensity and the other two are absent, -the pure respective color is obtained. -</para><para> -Two more examples: if both red and green are emitted at 100 percent and blue -is not emitted, pure yellow is obtained. A color with all three components at -the same intensity is a shade of gray. -</para><para> -There are various colorspaces that implement the RGB model. For example, the -so-called RGB8 colorspace represents each color with 8 bits per component. -Since 8 bits allow for 256 distinct values, the total number of different -colors that can be specified in this colorspace is 256 (red) * 256 (green) * -256 (blue), or about 16.7 million colors. In &krita;, a couple of RGB -colorspaces are available, for example RGB32, which is able to distinguish -between 4.2 billion values per component. -</para> - -</sect2> - -<sect2 id="colorspaces-list-cmyk"> -<title>The CMYK color model</title> - -<para> -CMYK is the abbreviation for Cyan, Magenta, Yellow, blacK (although officially -the K stands for Key, black is much more commonly used). This color model is -based on ink: a color is specified by the amount of ink needed for a point -to be perceived as having that color. -</para><para> -Since CMYK colors are used by printers while RGB colors are used on-screen, -one often wants to convert RGB colors to CMYK colors. As this cannot always be -done correctly, printed images may turn out to look quite different than what -is perceived on-screen. -</para> - -</sect2> - -<sect2 id="colorspaces-list-lab"> -<title>The L*a*b* color model</title> - -<para> -This color model uses three parameters for a color: its -luminance or lightness (L*, which lies between 0 for black and -100 for white), its position between absolute red and absolute green (a*, -which is negative for colors closer to green and positive for colors closer to -red), and its position between yellow and blue (b*, which is negative for -colors closer to blue and positive for colors closer to yellow). -</para> - -</sect2> - -<sect2 id="colorspaces-list-LMS"> -<title>The LMS color model</title> - -<para> -This model is based on the contribution of actual light wave lengths to the -color. The human eye is sensitive to three types of light waves, distinguished -by their wave lengths: long (L), middle (M) and short (S) waves. The eye's -sensitivity for a certain color on these three wavelengths can be expressed in -L, M and S coordinates. -</para> - -</sect2> - -<sect2 id="colorspaces-list-YCbCr"> -<title>The YCbCr color model</title> - -<para> -The YCbCr model is often used for video systems. The Y parameter indicates the -luminance or lightness of the color (which can be seen as a gray-tone), the Cb -and Cr parameters indicate the chrominance (color tone): Cb places the color -on a scale between blue and yellow, Cr indicates the place of the color -between red and green. -</para> - -</sect2> - -<sect2 id="colorspaces-list-Gray"><title>The Gray color model</title> - -<para> -The Gray color model simply represents colors as shades of gray (with black -and white being the extremes). -</para> - -</sect2> - -</sect1> - -</chapter> |